1. Field of the Invention
Embodiments of the invention generally relate to a method and apparatus for multilayer filmstack removal processing of metal and silicon materials in-situ. The invention is particularly useful for thin film transistor fabrication for flat panel displays.
2. Background of the Related Art
Substrate processing is typically performed by subjecting a substrate to a plurality of sequential processes to create devices, conductors and insulators on the substrate. Each of these processes is generally performed in a process chamber configured to perform a single step of the production process. A number of process chambers are typically coupled to a central transfer chamber that houses a robot to facilitate transfer of the substrate between the process chambers, thereby facilitating efficient completion of a sequence of processing steps in a processing platform. A processing platform having this configuration is generally known as a cluster tool, examples of which are the families of AKT PECVD, PRODUCER®, CENTURA® and ENDURA® processing platforms available from Applied Materials, Inc., of Santa Clara, Calif.
Generally, a cluster tool comprises a central transfer chamber having a robot disposed therein. The transfer chamber is generally surrounded by one or more process chambers. The process chambers are generally utilized to process substrates, for example, performing various processing steps such as etching, physical vapor deposition, ion implantation, lithography and the like. The transfer chamber is sometimes coupled to a factory interface that houses a plurality of removable substrate storage cassettes, each of which houses a plurality of substrates. A load lock chamber is disposed between the transfer chamber and the factory interface to facilitate transfer of a substrate between a vacuum environment of the transfer chamber and a generally ambient environment of the factory interface.
Glass substrates utilized in flat panel processing, such as those utilized to fabricate computer monitors, large screen televisions and displays for PDAs and cell phones and the like, are becoming dramatically larger as the demand for flat panels increases. For example, glass substrates utilized for flat panel fabrication have increased in area from 550 mm×650 mm to 1500 mm×1800 mm in just a few years, and are envisioned to exceed four (4) square meters in the near future.
Processing systems (e.g., cluster tools) have also increased in size to accommodate processing such large substrates. For example, the internal diameter of a transfer chamber utilized to move such large substrates between processing chambers in a typical cluster tool has increased from about 80 to about 135 inches to accommodate the substrate size. Thus, the cost associated with tooling configured to process large area substrates continues to escalate dramatically.
One structure typically formed on large area substrates is a transistor. In conventionally fabricated transistors, sequential process steps generally include metal and silicon etching, deposition, patterning and etching steps repeated multiple times. FIG. 14 is a flow diagram of an exemplary conventional transistor fabrication process. As the metal etching, silicon etching, and deposition processes are typically performed in separate cluster tools, the cost for fabricating transistors on large area substrates is high due to the number and size of tools, and the additional expense of transferring the substrate between tools during processing. Moreover, the number of substrate transfers between tools has an adverse effect on product yields due to the increase potential for contamination as the substrate is removed from the vacuum environment of one cluster tool for transfer to the next cluster tool required for the processing sequence. Thus, the continued utilization of multiple tools for transistor fabrication is undesirable, particularly in light of the significant investment by the manufacturer represented in each large area substrate.
Therefore, there is a need for an improved method and apparatus for multilayer film stack processing of substrates.